CIS no start issue -'77 911S

[timmy2]

Wow, looks like whiskey! From the picture I think you have found a problem. Looks like you may have a fun solution in the lower right corner...Unless that's to protect the still!

Check valve and/or accumulator from everything I've read. Cis primer explains the functions well.

[djb25]

STILL no luck!

I drained about 18 gallons of caramel colored fuel out of the car last night (see the photo I posted earlier).

The car still refuses to start.

I pulled all the plugs and cleaned them, thinking that I may have fouled them with all the previous attempts. No change.

I'm pretty much stumped now.

Where on earth do I go from here?

Any advice - and I mean ANY - would be appreciated. Ask me questions, whatever. I am COMPLETELY stumped now.

- Damion

[al lkosmal]

Have you attempted to start the engine using starting fluid yet? This may help isolate a fuel from an ignition issue.
regards,
al

[djb25]

Originally Posted by al lkosmal

Have you attempted to start the engine using starting fluid yet? This may help isolate a fuel from an ignition issue.
regards,
al

I have tried starting fluid. No go with the starting fluid, either.

I guess it could be an ignition issue, but I don't know what else to test with regard to the ignition. I have brand new Bosch copper plugs in the car now. I have spark at the coil and at each individual plug. I pulled the distributor out and did the test for the Petronix ignitor (using a multimeter).

Is there something I am missing, re: testing the ignition?

[timmy2]

I don't know if I would call this advice or something else but here goes:

Here is what I did to get my car to start on Sunday (4 days ago)when I had a huge vacuum leak due to my own error after R&R of the entire CIS system.
Taught me a lesson I'll never forget and I will never repeat the same mistake that had me going down this road.
(Not for the faint at heart)
Write down everything you do, so you can undo it.
1. Turn your richness screw with a 3mm wrench 1 complete turn clockwise, try to start, if it sounds like it wants to catch open the airscrew one or more entire turns, try to start again.
If it doesn't work, repeat and richen the mix again.
I had to richen my mixture 4 complete 360 degree turns and open the airscrew about 8 turns to get my car to start and run with the hose off the AAR as I mentioned in an earlier post in this thread.
Found the reason and fixed it, undid all the adjustments I made and she runs well again.
Proof positive that you can mask a vacuum leak by increasing the richness and adjusting the air mixture screw.

My theory for you to try this is to prove it can run and that you may have a CIS vacuum problem that you haven't found yet.

I had my airbox off because of a suspected leak (besides the one I put in it on re-assembly). I completely disassembled the airbox and plugged all holes and vacuum tested it.
I know I don't have a vacuum leak anywhere. (new boots and CIS component seals too!)

You decide if you want to try it. I can offer suggestions for pulling the CIS with the engine in car if you need them.

I'm starting to want to see that car running almost as much as you are!

[djb25]

Originally Posted by timmy2

Have you fixed the residual fuel pressure immediately going to zero by replacing the accumulator?

Up until last night I had been more or less ignoring the residual pressure issue because my fuel pump runs when the ignition is turned on.

However, because I'm running out of options, I checked the fuel accumulator last night. The bottom fitting holds vacuum without any leaking. I think this means that the accumulator checks out.

So I next checked residual pressure with the valve on my pressure tester closed. It holds right at the system pressure of 70 psi.

I did some more reading and then pulled out the "primary pressure valve" in the fuel distributor. It was immaculately clean. More importantly, it is of the "single spring" type.

At this point I realized I'm chasing my tail. The WUR outlet goes directly back to the fuel tank. There are no check valves or regulators AFTER the WUR. The only possible source for residual pressure loss would be the WUR itself.

The fuel pump check valve, the fuel accumulator, and the PPV are all upstream of the WUR.

Sure enough - the 911 workshop manual confirms this - if the residual pressure does not drop when the valve is closed (position 3 in the manual) the problem can be in the [warm up regulator] or control pressure regulator. Since my car does not have a control pressure regulator, that leaves the WUR.

The manual says the test for the WUR is to disconnect the WUR outlet (with the fuel pump shut off). If it leaks with a residual pressure between 1.5 and 2.4 bar, the WUR has failed. Of course, if the residual pressure is zero, that would suggest the same thing.

I also see that around 1978 Porsche added a check valve to the PPV and routed the WUR outlet to that check valve. Apparently they found that the WUR doesn't do a great job when it is acting as a check valve. This actually makes sense, since prior to '76 the residual pressure shouldn't have been much of an issue, but once they added the microswitch for the fuel pump, the retained pressure became a more significant problem.

Unfortunately, none of this solves my problem. However, it is one more thing to cross off the list.

Of course, it does raise a few other questions - for example - why on earth was my control pressure zero before I cleaned out the WUR?

Also - why is the WUR not retaining any residual pressure?

I have a theory on this - I have my cold control pressure set at 11 psi. If I'm understanding the system correctly, this would mean that the pressure valve is only exerting a small amount of pressure on the fuel flow. Put another way, the WUR is permitting the vast majority of fuel to flow through the WUR and back to the tank. A pressure drop is expected after the pump is shut off, so maybe with a warm WUR I would have some residual pressure.

Anyway, sorry for the long post. I'm still looking for advice, hints, or tips.

One question - is there a "baseline" setting for the mixture screw? My car obviously had its fuel injection messed with in a past life, and I have no idea where I'm working from with some of these settings.

[boyt911sc]

You are doing it all wrong!!!!! Please send the WUR to me and I'll have it tested ASAP. Right now, I have four (4) WUR's from Pelican members that I'm testing this weekend. Include the return address with stamps. This is not FREE. I'm charging you $0.10 for the work. Take note of the stamped numbers on the WUR. The casting #980 or 916, Germany/France plus the three (3) digits. Do not confuse the marking with 0-438-140-xxx. PM me.

Tony

[djb25]

Originally Posted by boyt911sc

You are doing it all wrong!!!!! Please send the WUR to me and I'll have it tested ASAP. Right now, I have four (4) WUR's from Pelican members that I'm testing this weekend. Include the return address with stamps. This is not FREE. I'm charging you $0.10 for the work. Take note of the stamped numbers on the WUR. The casting #980 or 916, Germany/France plus the three (3) digits. Do not confuse the marking with 0-438-140-xxx. PM me.

Tony

What am I doing wrong?

Do you mean I'm testing the fuel pressure incorrectly?

I need you to be a bit more specific.

Thanks,
Damion

[ossiblue]

Originally Posted by djb25

Up until last night I had been more or less ignoring the residual pressure issue because my fuel pump runs when the ignition is turned on.

However, because I'm running out of options, I checked the fuel accumulator last night. The bottom fitting holds vacuum without any leaking. I think this means that the accumulator checks out.

So I next checked residual pressure with the valve on my pressure tester closed. It holds right at the system pressure of 70 psi.

I did some more reading and then pulled out the "primary pressure valve" in the fuel distributor. It was immaculately clean. More importantly, it is of the "single spring" type.

At this point I realized I'm chasing my tail. The WUR outlet goes directly back to the fuel tank. There are no check valves or regulators AFTER the WUR. The only possible source for residual pressure loss would be the WUR itself.

The fuel pump check valve, the fuel accumulator, and the PPV are all upstream of the WUR.

Sure enough - the 911 workshop manual confirms this - if the residual pressure does not drop when the valve is closed (position 3 in the manual) the problem can be in the [warm up regulator] or control pressure regulator. Since my car does not have a control pressure regulator, that leaves the WUR.

The manual says the test for the WUR is to disconnect the WUR outlet (with the fuel pump shut off). If it leaks with a residual pressure between 1.5 and 2.4 bar, the WUR has failed. Of course, if the residual pressure is zero, that would suggest the same thing.

I also see that around 1978 Porsche added a check valve to the PPV and routed the WUR outlet to that check valve. Apparently they found that the WUR doesn't do a great job when it is acting as a check valve. This actually makes sense, since prior to '76 the residual pressure shouldn't have been much of an issue, but once they added the microswitch for the fuel pump, the retained pressure became a more significant problem.

Unfortunately, none of this solves my problem. However, it is one more thing to cross off the list.

Of course, it does raise a few other questions - for example - why on earth was my control pressure zero before I cleaned out the WUR?

Also - why is the WUR not retaining any residual pressure?

I have a theory on this - I have my cold control pressure set at 11 psi. If I'm understanding the system correctly, this would mean that the pressure valve is only exerting a small amount of pressure on the fuel flow. Put another way, the WUR is permitting the vast majority of fuel to flow through the WUR and back to the tank. A pressure drop is expected after the pump is shut off, so maybe with a warm WUR I would have some residual pressure.

Anyway, sorry for the long post. I'm still looking for advice, hints, or tips.

One question - is there a "baseline" setting for the mixture screw? My car obviously had its fuel injection messed with in a past life, and I have no idea where I'm working from with some of these settings.

A few comments.

First, take Tony up on his WUR testing or, at least, PM him and get specific with your questions. He has done lots of hands-on work with CIS and knows what he is doing.

Second, the WUR is the control pressure regulator--it goes by both names, the most common on this board is WUR.

Third, you apparently know how to do the pressure tests correctly. Currently, you have a residual pressure of "0", correct? When you cleaned out the WUR, did you replace the 0-ring in the diaphragm cover? (Sorry, I did not go back and re-read the entire thread.) Did you inspect the two diaphragms for any bends?

Fourth, 11psi is very low, below 1 bar. Most specs on residual pressure are ~1 bar so from the outset you are low. However, a functioning wur should still hold that pressure.

Finally, you might try the following and report back: You say your fuel pump runs with the ignition on (even though it shouldn't). When you try to start the car and it fails to fire, immediately shut it down and go pull the plugs--what do you see and smell? Are they gas soaked or dry or something in between? Remember, every time you crank the engine, raw gas is shooting into all the intakes at once. If you are not burning off that gas, it is accumulating in the cylinders and seeping into the crankcase and into the exhaust. You put in new plugs, so you should be able to see signs of ignition, if it's present.

The fact that you can't get ignition using ether makes me suspect fuel delivery may not be the major factor here.

[boyt911sc]

Originally Posted by djb25

What am I doing wrong?

Do you mean I'm testing the fuel pressure incorrectly?

I need you to be a bit more specific.

Thanks,
Damion

Damion,

Since you asked, I reluctantly will tell you to:
1). Establish that ignition sparks is produced during cranking!!!!! And reproducible.
2). Forget the rest of the CIS troubleshooting for they would be useless until you confirm this requirement (ignition sparks).
3). Run the FP and measure the control, system and residual pressures. Record the cold control fuel pressures from start (cold) till it stabilizes and may take 4 or 5 mins. Continue the observation until the cold control fuel pressures becomes the WCP. This is a critical test because these data would be your baseline data for your WUR.
4). Leave the air mixture screw alone at this point. This is used for fine tuning with a gas analyzer unless someone has disassembled the air metering unit before and you are starting from a rebuild.
5). How did you confirm that you don't have any vacuum/air leak? Not being able to see one does not mean you don't have any!!!! Test and confirm.

Lastly, your FP should NOT be running with the ignition switch @ ON position. There is something very wrong with your set-up (electrical). Your understanding of a WUR is flawed. It is not a check valve unit but rather a pressure regulator device. We could debate and discuss about the literature but let's put it aside and focus on the culprit/s. Keep us posted.

Tony

[djb25]

Originally Posted by ossiblue

A few comments.

First, take Tony up on his WUR testing or, at least, PM him and get specific with your questions. He has done lots of hands-on work with CIS and knows what he is doing.

Second, the WUR is the control pressure regulator--it goes by both names, the most common on this board is WUR.

Third, you apparently know how to do the pressure tests correctly. Currently, you have a residual pressure of "0", correct? When you cleaned out the WUR, did you replace the 0-ring in the diaphragm cover? (Sorry, I did not go back and re-read the entire thread.) Did you inspect the two diaphragms for any bends?

Fourth, 11psi is very low, below 1 bar. Most specs on residual pressure are ~1 bar so from the outset you are low. However, a functioning wur should still hold that pressure.

Finally, you might try the following and report back: You say your fuel pump runs with the ignition on (even though it shouldn't). When you try to start the car and it fails to fire, immediately shut it down and go pull the plugs--what do you see and smell? Are they gas soaked or dry or something in between? Remember, every time you crank the engine, raw gas is shooting into all the intakes at once. If you are not burning off that gas, it is accumulating in the cylinders and seeping into the crankcase and into the exhaust. You put in new plugs, so you should be able to see signs of ignition, if it's present.

The fact that you can't get ignition using ether makes me suspect fuel delivery may not be the major factor here.

1. I'm going to PM Tony and see what he suggests.

2. I was referring to the workshop manual testing procedure - earlier CIS cars had two control pressure regulators - the WUR and another on the throttle.

3. I did not replace the o-ring. No problems that I could see with the diaphragms.

4. I agree that the pressure is low. I found a chart that showed a very low cold pressure for the '77 911, and I thought I would try that pressure. No change.

5. What are the "signs of ignition" that I should be looking for?

Honestly, I agree that it seems like more of an ignition issue than a fuel issue, but I simply do not know what else to test with the ignition. Spark at all six plugs and I checked the gaps (again). Tested the distributor (and installed it 180 degrees out of timing at one point). Nice bright blue spark at coil. Is there something else I should look for?

[boyt911sc]

Originally Posted by djb25

Okay, I went crazy with air leak testing and found nothing. I even went as far as to remove the intake boot and cap off the throttle body (and aav). I could not locate any leaks. I did find that the pop-off valve leaked a little bit around the rubber o-ring when under pressure, but a slight amount of pressure eliminated the leak. If I pulled up on the valve slightly, I got gigantic bubbles immediately, so my soapy water solution was apparently functional.

Next I checked spark at each of the plugs. I found a nice, healthy blue spark at each plug.

Next I thought that perhaps I had the timing off by 180 degrees, so I reset the static timing. That change resulted in a very, very loud backfire (through the exhaust, not the intake). I'm guessing that the timing was correct.

Next I tapped the WUR pin down and reduced my cold control pressure to about 11 psi, which is another setting that I found for the '77 911S. Again - no change.

Next I pulled three injectors (cylinders 1, 2, and 4 - the easiest to reach). I tested each spray pattern. All three patterned well and none of them leaked. I can pull the other three, or all six and test their flow rate, but could one or two bad injectors cause this no start problem?

I'm about to lose my mind here.

One thing I haven't mentioned - my Optima battery is about shot. It won't hold a charge so I've been jumping the car off of my truck. Could the battery be causing a problem somehow?

The last possible thing I can think of = bad fuel. The fuel in the tank is fairly old... I can't say how old, but it's definitely from sometime last year. Should I drain the tank and replace it with fresh fuel? Does the ethanol blend cause more longevity issues?

I never had starting issues with this car in the past. I used to pull it out of winter storage and it would start almost immediately.

Damion,

If your ignition timing was 180° off you'll never be able to drive your car to the shop or start the engine!!!!!! So leave the air mixture setting and distributor out of your troubleshooting. They are good.

I'm putting my money on two things:
1. A significant air /vacuum leak some where that is affecting the combustion of the fuel-air mixture.
2. Ignition problem.

I'm re-reading your posts and noted the above.

Tony

[boyt911sc]

Damion,

The '87 Carrera that I bought for my son who lives in Carmel, CA will be driven cross country very soon. Need to drive the car more and get confident that it could take the long drive (3600 miles) to CA. I would not hesitate if I am taking my '78 SC but this '87 Carrera is new to me. What's your zip code?

Tony

[djb25]

Originally Posted by boyt911sc

Damion,

Since you asked, I reluctantly will tell you to:
1). Establish that ignition sparks is produced during cranking!!!!! And reproducible.
2). Forget the rest of the CIS troubleshooting for they would be useless until you confirm this requirement (ignition sparks).
3). Run the FP and measure the control, system and residual pressures. Record the cold control fuel pressures from start (cold) till it stabilizes and may take 4 or 5 mins. Continue the observation until the cold control fuel pressures becomes the WCP. This is a critical test because these data would be your baseline data for your WUR.
4). Leave the air mixture screw alone at this point. This is used for fine tuning with a gas analyzer unless someone has disassembled the air metering unit before and you are starting from a rebuild.
5). How did you confirm that you don't have any vacuum/air leak? Not being able to see one does not mean you don't have any!!!! Test and confirm.

Lastly, your FP should NOT be running with the ignition switch @ ON position. There is something very wrong with your set-up (electrical). Your understanding of a WUR is flawed. It is not a check valve unit but rather a pressure regulator device. We could debate and discuss about the literature but let's put it aside and focus on the culprit/s. Keep us posted.

Tony

Tony,

Thanks for the info. Here are my replies:

1) Spark is being produced during cranking. I checked it at all six plugs (with the assistance of the wife).

2) If there is some other ignition test for me to try, let me know. I'm all for it.

3) I have not done a check from cold to warm on the WUR. I did test the resistance a few times. I'll do this next.

4) Ok.

5) I pressurized the intake using the vacuum line that runs to the brake booster (I think that is where it goes - it connects below the throttle body and is a large sized hose). I sprayed everything repeatedly with a soap and water solution and could not find any leaks (other than around the pop-off valve and through the metering plate). Still not certain, I removed the intake boot and plugged the large hose that attaches in the back of the boot. I also capped the throttle body. Still couldn't find any leaks. So I then went and duct-taped my shop vac to the vacuum line and - don't laugh too hard - blew cigar smoke all over the engine. I checked to see if this would work by lifting the pop off valve slightly and it sucked in smoke readily. I'm not saying that there are no leaks, but I don't think there is a really large leak anywhere. But maybe there is... ?

6) I know the fuel pump should not run with the ignition. The car has been "rigged" like that since I bought it 12 years ago. I never bothered to figure out how they rigged it up that way, but the microswitch was completely removed.

[djb25]

Originally Posted by boyt911sc

Damion,

If your ignition timing was 180° off you'll never be able to drive your car to the shop or start the engine!!!!!! So leave the air mixture setting and distributor out of your troubleshooting. They are good.

I'm putting my money on two things:
1. A significant air /vacuum leak some where that is affecting the combustion of the fuel-air mixture.
2. Ignition problem.

I'm re-reading your posts and noted the above.

Tony

The distributor was off 180 degrees at one point after I pulled it out to test the ignitor. It was fairly easy to determine - huge backfire.

[djb25]

Originally Posted by boyt911sc

damion,

the '87 carrera that i bought for my son who lives in carmel, ca will be driven cross country very soon. Need to drive the car more and get confident that it could take the long drive (3600 miles) to ca. I would not hesitate if i am taking my '78 sc but this '87 carrera is new to me. What's your zip code?

Tony

15845.

[Howard M]

Check the back (towards front of the car) of the pop-off valve cement joint using a dental mirror. It's impossible to see without the mirror.

[boyt911sc]

Damion,

The pressure test would only work if you successfully inject positive air pressure into the system. This means the air metering unit should be excluded and plug all the hoses after removing the CIS rubber boot (throttle body to air metering unit). Install a latex glove on the throttle body and secure it.

Since you are doing the test and we have no idea what's going on except what you tell us, feedback is critical. Could you demonstrate (picture) that you are able to maintain a positive air pressure with 2 psi air supply? The latex glove should be inflated and maintain that condition during the test. Keep us posted.

Tony

[al lkosmal]

Since you have determined that you are getting both fuel and spark... and you are not getting it to start, using starting fluid....I am going to suggest that you have an ignition timing issue. You say that you are getting spark, but have you determined, using a timing light, that your timing is correct.

regards,
Al

[boyt911sc]

Damion,

I re-read your posts several times to determine what's been done in your troubleshooting saga. In your post #26 (3rd paragraph), you mentioned how you checked the residual fuel pressure. That's not the way to check the residual fuel pressure for CIS!!!!! First you have to measure and determine what's your control fuel pressure and start from there. You are not doing the right procedure.

The test you did could be used to check the FA, FD primary relieve valve, and FP check valve but not the residual pressure for CIS start-up. You need to measure the residual fuel pressure with the valve OPEN not closed!!!!! Keep us posted.

Tony